Mobile devices, such as mobile (cellular) telephones, PDAs (Personal Digital Assistants), laptop computers, and (portable) gaming consoles increasingly have multiple functions. Modern mobile telephones, for example, are not only suitable for making telephone calls but often also include a calculator, a calendar, and even games. Mobile phone games are typically designed for a single player, involving only the mobile device they are played on. However, some types of games require multiple players, each player using his/her own device. Before a multiple player game can begin, the players have to be selected and, accordingly, their mobile devices have to be identified.
It is possible to identify other mobile devices using a stored phone list containing the telephone numbers of other mobile devices and the respective names of their owners. However, the phone list contains no information regarding the availability and proximity of the other mobile devices. If a multiple player game is to be played with a group of players who are located in each other's vicinity, for example within viewing distance, the mobile devices of that group have to be identified in another way. Of course it is possible to manually enter the telephone numbers of participating mobile devices, if these numbers are known. However, this is cumbersome and prone to errors, in particular when the telephone numbers have to be read aloud. Accordingly, there is a need for a simple yet effective identification mechanism for mobile devices located in each other's vicinity.
Such an identification mechanism can also be used in mobile devices other than mobile telephones, for example in PDAs, laptop computers and so-called notebook computers. An identification mechanism may not only be used in gaming applications, as PDAs and similar devices may in general need to identify other devices in order to initiate a transaction between the devices. An example of a transaction is exchanging information, such as data files, calendar appointments, and other information.
The identification mechanism would primarily be used for mobile devices which are located in each other's vicinity, as remote devices would not likely be involved in a multiple player game or data exchange. In particular, it is often desired to invite (the owner of) a mobile device to join a game or to exchange calendar data when (the owner of) the mobile device is in view. For the invited mobile device to join the game or exchange data, it first has to be identified. Accordingly, there is a need to automatically identify proximate mobile devices.
International Patent Application WO 2005/103862 (Motorola), for example, discloses a handheld electronic device which includes a context sensing circuit and a microprocessor. The context sensing circuit is capable of detecting contextual characteristics of the device, such as motion of the device or proximity to or contact with another object. The detected contextual characteristics are used to display a virtual physical representation, for example indicating the angle of the device relative to the horizon. A touch sensor is activated by contact with or close proximity to a foreign object, such as the user, and may be used to determine how the device is held by the user. An infra-red (IR) sensor may be used to sense proximity to other objects, including the user's body. These sensors only provide information regarding the presence of other objects, not regarding their identity.
United States Patent Application US 2002/0021278 (Hinckley et al.) discloses a device in which context values are derived from sensors. A proximity sensor uses infra-red (IR) light to detect the proximity of other objects. The proximity sensor includes an IR transmitter and an IR receiver, the strength of the received (scattered) IR light is assumed to be proportional to the distance to the other object. Again, this known proximity sensor is not used to provide information concerning the identity of proximate objects.
Some Prior Art devices are capable of reading information instead of determining the proximity of other objects. For example, European Patent Application EP 1 677 512 (Sharp) discloses a mobile telephone capable of reading bar codes and taking photographs. This known device is capable of recognising bar codes representing URLs (Uniform Resource Locators, that is, references to Internet addresses). These bar codes are therefore not used for identifying mobile devices.
British Patent Application GB 2 362 070 (Nokia) discloses a payment system using mobile communication devices in which the devices are capable of presenting bar codes on their screens, which bar codes may be presented to a service access point for identification purposes. A Bluetooth® connection is then set up with the identified mobile communication device, while expressly excluding other proximate mobile identification devices.
United States Patent Application US 2007/174243 (Fritz) discloses a mobile social search method using mobile telephone devices provided with cameras. The camera of a mobile telephone device captures a bar code representing a certain user interest, upon which the device sends data including the device's location to a central server. The server then searches for other mobile devices having similar locations and having matching user interests. The respective locations of the mobile telephone devices are determined using GPS (Global Positioning System) or triangulation. As a result, this known method requires the mobile telephone system to determine the positions of the devices, and then determine which other devices are within the proximity of the mobile telephone device that scanned the bar code. Accordingly, this known method burdens the mobile telephone network with matching the proximate devices. In addition, the locations determined using GPS and in particular triangulations may be inaccurate, leading to undesired “matches”.